Does it make sense for me to get a used 7DmkII?

[e1rik1]

I have an EOS R, and recently got a EF 400mm f2.8 IS II. The combo works pretty well!

I remember reading reviews a long time ago that 7DmkII was the ideal companion to this lens.
Given that I can see used copies online for less than 300$, does it make sense to get one? Will the sensor performance be dramatically worse than the EOS R?

Is there much to gain with AF speed and tracking? I'm sure the slightly extra reach will be nice!

[rs-eos]

If you've already spent the cash on a EF 400mm f/2.8, (even if used, it would be quite a bit), I would recommend looking at a crop-sensor R-series body (e.g. EOS R7) instead.

[shadowsports]

Agree with Ricky 👍  Excellent suggestion.  

If you are not convinced.  

33 vs 20MP - great for cropping

651 vs 65 Cross type AF Points - Wil take Animal AF and BIF to new levels.

32000 vs 16000 ISO - While the 7D2 hs dual Digic 6's the R7's one Digic X can run circles around it.  

15 vs 10 FPS, 4K video, Wireless.  The R7 is more money, but its a lot more camera too.    Its a better investment and future proof for the type of wildlife photography you enjoy.